1. Field of the Invention
The present invention relates to a network for distribution of data, and more particularly to a network including a programmable logic controller with at least one input/output unit that are interconnected with a distributor, e.g., and Ethernet switch, and active taps using a bus line.
2. Description of the Related Technology
Field bus systems (such as a profibus or an actuator/sensor interface bus) are conventionally used for communications between programmable logic controllers (SPS) and input/output units in industry, for example within a machine These field bus systems can be implemented in two ways.
First, each terminal device, e.g., input/output unit, can have two connection points for a field bus connection, cabling thus taking place directly from device to device, and one of the devices being connected to a programmable logic controller. The second possibility is for the field bus to have a main line from which so-called branch points are located at corresponding connection points for terminal devices, each respective terminal device being connected to its pertinent branch point.
These field bus systems have proven themselves in practice. However, these field bus systems have a maximum possible transmission rate of only up to 10 megabits per second, this processing speed and the resulting data volume is no longer adequate for current applications. The low transmission rates are due to the fact that interfaces of terminal devices or branch points are built passively, so that an increase in the amount of transmitted data or the processing speed is not possible with these components.